Commit b2ca916c authored by Dan Williams's avatar Dan Williams
Browse files

ACPI: NUMA: Up-level "map to online node" functionality 



The acpi_map_pxm_to_online_node() helper is used to find the closest
online node to a given proximity domain. This is used to map devices in
a proximity domain with no online memory or cpus to the closest online
node and populate a device's 'numa_node' property. The numa_node
property allows applications to be migrated "close" to a resource.

In preparation for providing a generic facility to optionally map an
address range to its closest online node, or the node the range would
represent were it to be onlined (target_node), up-level the core of
acpi_map_pxm_to_online_node() to a generic mm/numa helper.

Cc: Michal Hocko <mhocko@suse.com>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/158188324802.894464.13128795207831894206.stgit@dwillia2-desk3.amr.corp.intel.com
parent bb6d3fb3

drivers/acpi/numa/srat.c

+0 −41
Original line number Diff line number Diff line
@@ -72,47 +72,6 @@ int acpi_map_pxm_to_node(int pxm) 
}

EXPORT_SYMBOL(acpi_map_pxm_to_node);



/**

 * acpi_map_pxm_to_online_node - Map proximity ID to online node

 * @pxm: ACPI proximity ID

 *

 * This is similar to acpi_map_pxm_to_node(), but always returns an online

 * node.  When the mapped node from a given proximity ID is offline, it

 * looks up the node distance table and returns the nearest online node.

 *

 * ACPI device drivers, which are called after the NUMA initialization has

 * completed in the kernel, can call this interface to obtain their device

 * NUMA topology from ACPI tables.  Such drivers do not have to deal with

 * offline nodes.  A node may be offline when a device proximity ID is

 * unique, SRAT memory entry does not exist, or NUMA is disabled, ex.

 * "numa=off" on x86.

 */

int acpi_map_pxm_to_online_node(int pxm)

{

	int node, min_node;



	node = acpi_map_pxm_to_node(pxm);



	if (node == NUMA_NO_NODE)

		node = 0;



	min_node = node;

	if (!node_online(node)) {

		int min_dist = INT_MAX, dist, n;



		for_each_online_node(n) {

			dist = node_distance(node, n);

			if (dist < min_dist) {

				min_dist = dist;

				min_node = n;

			}

		}

	}



	return min_node;

}

EXPORT_SYMBOL(acpi_map_pxm_to_online_node);



static void __init

acpi_table_print_srat_entry(struct acpi_subtable_header *header)

{

include/linux/acpi.h

+22 −1
Original line number Diff line number Diff line
@@ -416,9 +416,30 @@ extern void acpi_osi_setup(char *str); 
extern bool acpi_osi_is_win8(void);



#ifdef CONFIG_ACPI_NUMA

int acpi_map_pxm_to_online_node(int pxm);

int acpi_map_pxm_to_node(int pxm);

int acpi_get_node(acpi_handle handle);



/**

 * acpi_map_pxm_to_online_node - Map proximity ID to online node

 * @pxm: ACPI proximity ID

 *

 * This is similar to acpi_map_pxm_to_node(), but always returns an online

 * node.  When the mapped node from a given proximity ID is offline, it

 * looks up the node distance table and returns the nearest online node.

 *

 * ACPI device drivers, which are called after the NUMA initialization has

 * completed in the kernel, can call this interface to obtain their device

 * NUMA topology from ACPI tables.  Such drivers do not have to deal with

 * offline nodes.  A node may be offline when a device proximity ID is

 * unique, SRAT memory entry does not exist, or NUMA is disabled, ex.

 * "numa=off" on x86.

 */

static inline int acpi_map_pxm_to_online_node(int pxm)

{

	int node = acpi_map_pxm_to_node(pxm);



	return numa_map_to_online_node(node);

}

#else

static inline int acpi_map_pxm_to_online_node(int pxm)

{

include/linux/numa.h

+9 −0
Original line number Diff line number Diff line
@@ -13,4 +13,13 @@ 


#define	NUMA_NO_NODE	(-1)



#ifdef CONFIG_NUMA

int numa_map_to_online_node(int node);

#else

static inline int numa_map_to_online_node(int node)

{

	return NUMA_NO_NODE;

}

#endif



#endif /* _LINUX_NUMA_H */

mm/mempolicy.c

+30 −0
Original line number Diff line number Diff line
@@ -127,6 +127,36 @@ static struct mempolicy default_policy = { 


static struct mempolicy preferred_node_policy[MAX_NUMNODES];



/**

 * numa_map_to_online_node - Find closest online node

 * @nid: Node id to start the search

 *

 * Lookup the next closest node by distance if @nid is not online.

 */

int numa_map_to_online_node(int node)

{

	int min_node;



	if (node == NUMA_NO_NODE)

		node = 0;



	min_node = node;

	if (!node_online(node)) {

		int min_dist = INT_MAX, dist, n;



		for_each_online_node(n) {

			dist = node_distance(node, n);

			if (dist < min_dist) {

				min_dist = dist;

				min_node = n;

			}

		}

	}



	return min_node;

}

EXPORT_SYMBOL_GPL(numa_map_to_online_node);



struct mempolicy *get_task_policy(struct task_struct *p)

{

	struct mempolicy *pol = p->mempolicy;

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